The overall goal of this project is a better understanding of the ultrastructural and chemical changes which characterize the development of human cataracts. The cause of fiber cell destruction, during the development of human cataracts, is a main aspect of the proposal. This would include an ultrastructural analysis of 1) the process of lens fiber cell disintegrated seen with S.E.M., T.E.M. and freeze-etch E.M., and 2) the formation of intercellular spaces, and the analysis of their contents with energy dispersive X-ray analysis. A major effort will be made to correlate specific ultrastructural and chemical findings with the presence of specific lens opacities, classified according to established Cooperative Cataract Research Group procedures (C.C.R.G., NEI.) A systematic study of the normal human lens, obtained primarily through the Michigan Eye Bank located within the Kresge Eye Institute, is proposed as a basis of comparison with the cataractous lens. This would include a study of junctional complexes (gap junctions and tight junctions) as seen primarily with freeze-etch E.M. and other surface structural characteristics (S.E.M. and T.E.M.) at specific, defined locations within the lens. The sulfur-phosphorus data (and more recently the data on calcium localization) obtained in this laboratory indicate that energy-dispersive X-ray analysis can be an effective tool in elemental analysis within specific structures of the lens. Correlation of the location of the phosphorus-containing material with ultrastructural characteristics, and the presence of opacities as seen in the C.C.R.G. light microscope stereophotographs may indicate, for example, whether the phosphorus-containing material is associated with plasma membrane fragments, and how it relates to lens opacities. Attempts will be made to determine the cause of calcium-containing opacities in the human lens from existing medical records and patient interviews. Also by means of quick-freeze preparation of tissues it is planned to extend our studies on elemental analysis to the diffusible ions, sodium, potassium and chloride in the normal and cataractous lens.